Field
Embodiments of the present invention generally relate to substrate supports used in processing chambers for fabricating microelectronic devices and, more specifically, to electrostatic chucks used in plasma processing chambers.
Description of the Related Art
In high precision manufacturing, for example semiconductor manufacturing, a workpiece may need to be precisely held by a fixture during manufacturing operations to increase uniform quality and reduce defects. In some manufacturing operations an electrostatic chuck may be used as the fixture to hold the workpiece against a supporting structure using an electrostatic force (“clamping force”) of the electrostatic chuck to precisely hold the workpiece during one or more manufacturing operations.
It is common in manufacturing operations that the workpieces in high-precision manufacturing operations should be held by a minimum clamping force as possible with the lowest possible contact to the workpiece to reduce defects. However, because of manufacturing variances such as surface treatments applied to workpieces that can change chucking force, and because of environmental effects, manufacturing personnel often increase the target clamping force to provide a factor of safety to ensure that at least a sufficient clamping force is being applied to counter the variances and effects.
A large majority of the electrostatic chucks used in semiconductor manufacturing industry are believed to apply clamping forces that are greater than required. This “overchucking” causes damage to the workpiece, for example, by causing craters in a backside of the workpiece, embedding parts of the electrostatic chuck into the workpiece, and/or causing particulates which cause quality problems on the frontside of the workpiece.
Conventional approaches to reduce the overchucking problems have included measuring an electrical potential of the workpiece before the clamping force is applied which can impact clamping force and utilizing an algorithm to compensate for the electrical potential of the workpiece to maintain a minimum clamping force. As manufacturing tolerances become increasingly tighter and the need to reduce costs becomes more important, new approaches are needed to provide a more consistent and predictable clamping force to accommodate a wider range of manufacturing variances.